Gene Is Biomarker for Colon Cancer

Cancer researchers have developed a screening test for a colon cancer biomarker that is about three times more sensitive than the currently used occult blood test.

Investigators at Case Western Reserve University (Cleveland, OH, USA) and Exact Sciences Corporation (Marlborough, MA, USA) focused their attention on the vimentin gene that is silent and unmethylated in normal cells but is active and methylated in colon cancer cells. They applied methylation-specific polymerase chain reaction (PCR) to the vimentin gene, and compared methylation of vimentin exon 1 in cancer tissues and in fecal DNA from colon cancer patients versus control samples from healthy subjects.

Results published in the August 3, 2005, issue of the Journal of the U.S. National Cancer Institute revealed that vimentin exon-1 sequences were unmethylated in 45 of 46 normal colon tissues. In contrast, vimentin exon-1 sequences were methylated in 83% and 53% of tumors from two independently collected groups of colon cancer patients. When evaluated as a marker for colon cancer detection in fecal DNA from another set of colon cancer patients, abnormal vimentin methylation was detected in fecal DNA from 46%. Detection of 46% of colon cancers by this method was significantly better than the 15% detected by the standard fecal occult blood test.

"We are now working with our collaborators at Exact Sciences to combine vimentin with other DNA markers to see if we can develop a panel of tests that will ultimately detect 100% of colon cancers,” said senior author Dr. Sanford Markowitz, professor of molecular biology and microbiology at Case Western Reserve University. "We hope that vimentin will be included in the near future as a powerful marker in a molecular panel for stool-based colon cancer screening and that it will further encourage mass screening.”




Related Links:
Case Western Reserve University
Exact Sciences